Give Some Details Of Extrusion Of Nylon?

A water cooled throat section is standard on most extruders. Its job is to prevent premature melting of the pellets and also to protect the thrust-bearing assembly on the extruder. The temperature of the throat section, for nylon, must always be slightly above room temperature. Should the throat be too cold, moisture vapor will condense on its surfaces (inside and outside) and moisture may be carried into the melt.
Nylon melts are not corrosive to metals and no special consideration for extruder materials of construction is required. being processed.) This is a good opportunity to check the operation of controllers.
When these zones reach the operating temperature, the remaining barrel zones, except the rear, are heated to the same temperature. The rear zone is deliberately kept below the melting point of the nylon resin to prevent overheating and possible bridging problems during start-up. Feed throat cooling water is turned on. Cooling of the entire screw is not recommended in processing nylon; however, cooling of the feed zone (5 flights) is effective in solving some specific feeding problems like erratic or non uniform feeding. When all zones have been at the desired temperatures for 20 to 30 minutes, the resin may be fed into the hopper. The screw should be turned on at a slow speed (5-10 rpm). When it has been established that the screw is picking up the resin properly, the barrel rear zone is raised to the desired operating temperature.
Until one becomes familiar with the specific nylon resin being extruded, it is suggested that the resin be hand fed gradually until melt appears at the die. At this point, the melt should be clear and the melt temperature should have leveled out. It is desirable to use a pressure gauge and an ammeter to monitor the extruder performance at start-up. For maximum safety of the equipment, the pressure gauge should be located between the end of the screw and the breaker plate.